Motor fuel containing substituted oxazoline compounds



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United States Patent Ofiice 3,033,663 Patented May 8, 1962 3,033,663 MOTOR FUEL CONTAINING SUBSTITUTED OXAZOLINE COMPOUNDS Richard J. De Gray, Shaker Heights, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Filed Feb. 26, 1958, Ser. No. 717,549

5 Claims. (Cl. 44-63) This invention relates to a motor fuel containing a multi-purpose additive comprising a substituted oxazoline compound of the general formula:

wherein R represents a saturated or unsaturated hydrocarbon radical containing 7 to 19 carbon atoms, and where R represents the radical (CH ),,OH where n is a small whole number such as l to 3, and where R represents a radical selected from the group consisting of R hydrogen, or a lower alkyl radical having 1 to 3 carbon atoms.

Salts of these mildly basic compounds have been suggested by the prior art for incorporation into liquid hydrocarbons and particularly slushing oils, lubricating oils, and grease compositions to provide corrosion inhibiting properties. Exemplary of this art is a corrosion preventive composition utilizing an oxazoline salt of ricinoleic acid, as disclosed in Patent No. 2,587,955.

It has been found, however, in accordance with this invention, that the oxazoline compounds of the general formula assigned above are excellent motor fuel additives in themselves when incorporated into the fuel in amounts as small as 0.0025% by weight. Furthermore, the compounds used in the fuel of this invention fill the criteria of a commercially desirable gasoline additive in that they offer a host of improvements without offsetting these gains with other efiects which are of harmful nature, and hence their selection for use is not merely a compromise of gaining certain advantages for the sacrifice of less important characteristics.

The fuel of this invention is particularly helpful in preventing a troublesome condition experienced by most cars operated today in urban areas. It is generally accepted in the art that harmful deposits accumulate in the carburetors of motor vehicles from contaminated intake air which the carburetor must breathe in by tremendousvolumes for engine operation. The major contributor to this responsible contamination in the air is believed to be the combustion products exhausted from the large population of other cars operating in the same immediate area. The condition is, of course, aggravated by any blowby fumes from the operation of the cars own engine or by any other under-hood fumes generated by the cars engine, in addition to any industrial fumes present in the air which the carburetor breathes. These sources of contamination are additive in nature and may cause the rapid buildup of deposits on the carburetor of the engine.

These deposits manifest themselves by causing rough idling of the engine and in many cases the occurrence of frequent stalling. Although the motor fuel itself is not responsible for these effects, it offers the most likely agency for introducing a material which may serve as a remedy for such an undesirable condition by preventing such deposit buildup in the carburetor.

It therefore is the aim of this invention to provide a fuel containing minor amounts of a class of oxazoline compounds which are effective in preventing deposits from forming in the carburetor of an internal combustion engine which would interfere with the normal operation of such an engine.

The further value of the fuels of this invention will be appreciated from the following discussion of ancillary benefits derived from their utilization in automotive engines.

Motor fuels containing these substituted oxazoline com pounds show marked effectiveness in reducing surface ignition. It is well recognized in the prior art that the continued operation of the internal combustion engine results in the formation of combustion chamber deposits. These deposits produce a number of adverse effects, notable among which is a tendency for these deposits to become heated to incandescence, developing one or more hot spots within the combustion chamber. These spots ignite the fuel either before or after the position in the cycle at which the fuel would normally be ignited by the spark of the sparkplug. This condition, referred to commonly as surface ignition, manifests itself in various ways characterized as different forms of knocking or engine roughness and usually resulting in appreciable power loss. A number of chemical compounds have the facility for eliminating in some degree this adverse effect of chamber deposits. It is believed that these compounds either remove part of the deposits so formed or in some manner modify the chemical nature of these deposits so as to minimize their adversity, or alter the combustion characteristics of the fuel so as to minimize abnormal combustion. Obviously in selecting any additive for gasoline, it is highly desirable that the additive be effective in reducing surface ignition.

characteristically, compounds which are desirable due to their effectiveness in reducing surface ignition often detract from their value by demonstrating a negative response to octane rating. With the current production costs for octane rating and the increasing pressure for octane improvement in fuels, many compounds, although effective in reducing surface ignition, cannot be justified due to their adverse effect on octane rating. Surprisingly, the oxazoline compounds are an exception to this generalization since their presence in the fuel not only reduces surface ignition but also produces an improvement in octane rating. These compounds as fuel additives thereby offer obvious economic as well as quality advantages.

A further benefit that these compounds offer in motor fuel is related to their effectiveness in minimizing carburetor icing. The latter condition represents another troublesome problem attendant to automotive engines operated in cool, moist, atmospheric conditions. This icing problem is most likely to occur during engine warmup When the engine is below normal operating temperature. Vaporization of the gasoline in the carburetor during this warmup period produces temperature reduction of the throttle plate and carburetor walls, causing the moisture present in the incoming air on cool, humid days to condense and freeze. Such ice formation restricts the narrow openings in the carburetor, manifiesting itself in a rough idling condition and frequent engine stalls.

The oxazolines used in this invention may be prepared from amino hydroxy compounds through their fatty amides or by any other procedure. In preparing the oxazolines from the fatty acid amides, a suitable amino hydroxy compound is reacted with a desirable fatty acid or a mixture thereof at an elevated temperature to yield the amide. The temperature is then increased so as to split out water and form the oxazoline. Further information regarding the preparation of these substituted oxazolines using this procedure is contained in Patent Nos. 2,372,409 and 2,372,410.

Any of the compounds having the general formula ofiered above are suitable for the invention. The preferred compounds, however, are those in which R as defined heretofore, contains 11 to 17 carbon atoms for maximum solubility in hydrocarbon fuels. Mixtures of compounds may be used, and this frequently will be the case since the R radical is derived from naturally occurring fats and oils and R will correspond to the fatty acid radicals in such fats and oils, such as tallow, cottonseed oil, soybean oil, tall oil, etc. Since the nature of R does not affect the results appreciably, its selection will be dictated largely by economics. The commercial grade of the compounds including small amounts of impurities or by-products are suitable. A particularly desirable compound for purposes of the invention is 2-heptadecenyl 4,4-bis-(hydroxy methyl) oxazoline and has the formula:

onion N-O Cr'lHas-O CHzOH and is referred to hereinafter as Oxazoline-T.

Other compounds useful in the invention and which are included as illustrative within the above formula are:

The hydrocarbon fuel base stocks to which these substituted oxazoline compounds are to be added may be any of those conventionally used in preparing a motor gasoline for internal combustion engines, such as catalytic distillate, motor polymer, alkylate, catalytic reformate, isomerate, naphthas, etc. It is intended that the gasoline of the invention may also contain tetraethyl lead in amounts up to 6 ml., generally up to 3 ml., but at least /2 ml. per gallon and a scavenging agent. In addition to the lead anti-detonant and a scavenger composition, the gasoline may also contain anti-oxidants, stabilizers, solvent oils, dyes, other additives such as boron compounds, and the like.

The amount of the substituted oxazolines to be added to the fuel may vary between 0.0025 by weight, which is the smallest amount that produces any significant effect, and 0.1% since amounts in excess of this concentration could not normally be justified economically. Amounts between 0.005% and 0.05% are usually to be preferred.

A clearer understanding of the benefits derived from the fuel of this invention will be obvious from the results obtained from the following testing programs.

Carburetor Cleanliness A test was devised to determine an effective rating for promoting carburetor cleanliness with the gasoline of the invention as compared with the same gasoline not containing an oxazoline compound. In this test a contamination system was developed to simulate the conditions which contribute to carburetor deposits in the urban operation of motor vehicles. The system comprises the operation of a slave engine and a test engine. The exhaust gases from one bank of the slave engine (four cylinders) is metered to the crankcase of the test engine at a rate of 1.5 cubic feet per minute. All gases from the crankcase of the test engine are passed to the air intake of the carburetor of the test engine including, therefore, the exhaust gases from the slave engine and the blowby fumes of the test engine. The 1.5 cubic feet per minute rate of exhaust gases from the slave engine under these conditions constitutes approximately 8% of the total air intake of the test engine at idle manifold vacuum and speed. The operating conditions for the two engines are as follows:

The test cycle was 2 hours in time, which included four acceleration periods conducted on the unloaded test engine spaced at /2 hour intervals, the first acceleration period being 30 minutes after the test cycle was commenced. During each acceleration period the throttle was moved quickly to a wide open position and then quickly closed again to an idle position five separate times to permit a surge of carburetted gasoline to come into contact with the carburetor parts. The carburetor at the start of each test was in spotless condition. All experimental conditions were the same for the two test cycles except for the gasoline.

The base fuel in each test was the same and had the following composition and specifications.

Composition:

75% ca-t. distillate 25 SR naphtha API gravity 62.4

Engler distillation:

IBP TL. 98 10% c F 130 30% F 163 50% F 204 70% F-.. 262 F 365 EP F 424 Reid vapor pressure 8.75

Additive l Rating OxazolineT at 0.05% by weight 93 None Surface Ignition Suppression To determine the efiectiveness of the gasoline of this invention to suppress surface ignition, an ASTM-CPR single-cylinder engine having the compression ratio adjusted at 12:1 was employed. Preparatory to the test cycle, the engine was run open throttle at 900 rpm. for thirty minutes to stabilize the engine conditions for the test period. Following this, the engine was continued at open throttle continuously for threehours, during which time the total surface ignition count was observed electronically. All experimental conditions were the same for each test except the gasoline.

The base fuel in each test was the same and had the following composition and specifications.

Composition: 59.8% Ultraforr'r'iat 30.0% cat. distillate 10.0% it. naphtha The number of surface ignitions in the additive fuel is expressed as percentage of the surface ignitions of the blank fuel with the results as follows:

SI Rating of Fuel, percent Additive Total SI Audible SI N 100 100 Oxazoline-T at 0.1% 51 89 Octane Improvement Two fuels having the compositions and physical characteristics as listed below were tested for octane rating by the F-1 and F-2 ASTM test methods with and without the oxazoline additive:

597 Lt. Alkylate 84% Cat. Reformate..- Composition 30% Benzene {16% Lt. Naphtha. 11% Toluene API Gravity 49.1

Engler Distillation:

IBP 114 120 153 168 206 186 250 196 296 208 356 232 EP 446 296 Reid Vapor Pressure 6.95 5. 05 Tetraethyl Lead (Motor 3. 1 3. 1

Mix) mL/gal.

The results of these tests are indicated below:

Octane Rating F-l F-Z Fuel A 99. 56 90.85 Fuel A Oxazoline-T at 0.05% by Weight 99. 69 91. 04 Fuel B 107. 66 101.18 Fuel B Oxazoline-T at 0.05% by Weight 107. 61 101. 34

In the 99+ octane fuel, typical of premium fuels today, both the F-1 and F-2 ratings are improved. The

numerical improvements indicated in these results are not large; yet considering the high octane levels of these base fuels, any further increase in octane number, particularly in the F-2 method, is significant. The important thing is that the oxazoline compounds, contrary to the observation with many compounds that suppress surface ignition such as many phosphorus compounds, do not lower the octane rating of the fuel.

Carburetor Anti-Icing A test procedure was devised simulating the stop-andgo type of engine operation normally experienced by the motorist during the engine warmup period. The test was conducted in a 1955 Plymouth V*8 engine equipped with a two-barrel carburetor. Carburetor air was supplied at a constant rate of 70 cubic feet per minute by a specially designed air conditioner controlled at 42 F. and relative humidity, which are temperature and humidity conditions considered highly conducive to carburetor icing. All test conditions were the same except for the gasoline.

The test consisted of running the same number of cycles on each fuel where in each cycle the engine was operated at 2200 r.p.m., for 15 seconds and then decelerated normally to an idle at 450 r.p.m. for a maximum of 30 seconds. Performance of the engine was observed during each idle period, and a numerical rating based on the degree of rough idling and engine stalls was assigned so that each fuel received a merit rating on a scale ranging from to 0. By this scheme an engine operating with a smooth idle over the idle periods of every test cycle would receive a rating of 100, and an engine which stalled in less than 12 seconds in the idle period of every test cycle would receive a rating of 0.

The base fuel used had the following composition and specifications.

Composition:

7 48.5% It. cat. distillate 28.9% Ultraformate 9.7% It. naphtha 4.9% isopentane 7.8% butane 0.2% solvent oil API gravity Engler distillation:

IBP 10% 30% 50% 70% 90% F EP 420 Reid vapor pressure 11.75

Tetraethyl lead (motor mix) ml./gal 3.0

The results of this test are as follows:

Additive Rating Since these compounds are readily soluble in gasoline, they may be incorporated directly into bulk gasoline at a refinery by standard mixing equipment. If a motorist wishes to use the compound in a fuel not made with the same at the refinery, a preferred method for incorporating these compounds into the motor fuel is in solution in a solvent compatible with gasoline. An appropriate volume of this solution may then be added to a filled fuel tank of a motor vehicle to provide the desired concentration of oxazoline. For example, if 12 ounces of solvent with 5% of the oxazolin compound is added to gallons of gasoline, the latter will contain approximately 0.05% of the oxazoline compound. Similarly, if 12 fluid ounces of solvent with 0.25%, 0.5 %,,and 10%, respectively, of the oxazoline compound are added to 10 gallons of gasoline, the latter will contain approximately 0.0025%, 0.005%, and 0.1% by weight, respectively, of the oxazoline compound. The solvent may be any hydrocarbon such as benzene or preferably any lower aliphatic alcohol having 1 to 4 carbon atoms, especially methanol and iso-propanol. Methanol, however, is the preferred alcohol since its addition to the fuel offers added benefits to the fuel. Due to methanols strong attraction for Water, it will aid measurably in preventing fuel line freezing in addition to providing added protection to the oxazoline compounds against water extraction before the fuel is used in the engine. Furthermore, methanol is known to enhance the carburetor antiicing behavior of a motor fuel. Despite the fact that methanol may preferentially mix with the water phase in a gasoline tank, if one is present, the oxazoline compound is contained in the gasoline phase.

I claim:

1. A gasoline for minimizing carburetor deposits con: taining 0.0025% to 0.1% by weight of a substituted oxazoline compound of the formula:

wherein R represents an aliphatic hydrocarbon radical containing 7 to 19 carbon atoms and where R represents the radical (CH OH where n is a small whole number and R represents a radical selected from the group consisting of R hydrogen, and a lower alkyl radical having 1 to 3 carbon atoms.

2. A gasoline for minimizing carburetor deposits containing /2 to 6 cc. of tetraethyl lead per gallon and 0.0025% to 0.1% by weight of a substituted oxazoline compound of the formula:

wherein R represents an aliphatic hydrocarbon radical containing 11 to 17 carbon atoms.

3. A method of minimizing the formation of deposits in the carburetor, which deposits result at least in part from contaminants present in the intake air to said carburetor, and otherwise improving the operation of said engine, comprising the steps of feeding to said carburetor a gasoline containing 0.0025% to 0.1% by weight of a substituted oxazoline compound of the formula:

O-CH:

wherein R represents an aliphatic hydrocarbon radical containing 7 to 19 carbon atoms and where R represents the radical (CH OH where n is a small whole number and R represents a radical selected from the group consisting of R hydrogen, and a lower alkyl radical having 1 to 3 carbon atom-s, and carburetting said intake air with said gasoline to provide a combustion mixture for the operation of said engine.

4. A method of minimizing the formation of deposits in the carburetor, which deposits result at least in part from contaminants present in the intake air to said carburetor, and otherwise improving the operation of said engine, comprising the steps of feeding to said carburetor a gasoline containing 0.0025 to 0.1% by weight of a substituted oxazoline compound of the formula:

CH2OH wherein R represents an aliphatic hydrocarbon radical containing 11 to 17 carbon atoms, and carburetting said intake air with said gasoline to provide a combustion mixture for the operation of said engine.

5. An additive concentrate for gasoline consisting essentially of a hydrocarbon solvent compatible with gasoline containing 0.25 to 10% by weight of a substituted oxazoline compound of the formula:

y NC/ Rr-C R- O-CH:

wherein R represents an aliphatic hydrocarbon radical containing 7 to 19 carbon atoms and where R represents the radical --(CH ),,OH where n is a small whole number and R represents a radical selected from the group consisting of R hydrogen, and a lower alkyl radical having 1 to 3 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,382,906 Pedersen et a1 Aug. 14, 1945 2,825,637 Jonach et al Mar, 4, 1958 2,839,371 Sigworth June 17, 1958 

1. A GASOLINE FOR MINIMIZING CARBURETOR DEPOSITS CONTAINING 0.0025% TO 0.1% BY WEIGHT OF A SUBSTITUTED OXAZOLINE COMPOUND OF THE FORMULA: 